An interpretation of EPR spectra of azide ligated superoxide dismutase from Propionibacterium shermanii

1995 ◽  
Vol 24 (2) ◽  
Author(s):  
O. Iakovleva ◽  
F. Parak ◽  
T. Rimke ◽  
B. Meier ◽  
J. H�ttermann ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Epr Spectra ◽  
Propionibacterium Shermanii

scholarly journals Kinetic and spectroscopic studies on a superoxide dismutase from Propionibacterium shermanii that is active with iron or manganese: pH-dependence

1995 ◽  
Vol 310 (3) ◽  
pp. 945-950 ◽  
Author(s):  
B Meier ◽  
C Michel ◽  
M Saran ◽  
J Hüttermann ◽  
F Parak ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Catalytic Activity ◽  
Ph Dependence ◽  
Anaerobic Bacteria ◽  
Bound Water ◽  
Kinetic Studies ◽  
Spectroscopic Studies ◽  
Epr Spectra ◽  
Superoxide Dismutases ◽  
Propionibacterium Shermanii

Kinetic studies were performed on the superoxide dismutases isolated from the anaerobic bacterium Propionibacterium shermanii as active enzymes with either iron or manganese, which were naturally incorporated into the same molecule depending on the metal supply. Both the Fe- and Mn- forms showed decreasing activity with increasing pH. This suggests the protonation of some groups near the metal, possibly a metal-bound water molecule. Thus the kinetic behaviour of this superoxide dismutase is much more dependent on the protein structure than on the metal incorporated into the active site. The secondary structures of both forms were not influenced by variations in pH, whereas the EPR spectra of the Fe-superoxide dismutase changed as a function of pH. The EPR spectra apparently consist of two overlapping species. Steady-state experiments proved that all iron-containing species show catalytic activity, but the species predominating in the alkaline pH range displays a lower reaction rate. The Michaelis constant and maximal turnover number for the Fe-superoxide dismutase were determined polarographically as Km = 0.54 mmol/l and Vmax. = 2000 mol.s-1 at pH 9.5. These data indicate that, in anaerobic bacteria under physiological conditions, the superoxide dismutase is not saturable with O2-. and the catalytic activity is similar to that of metal-specific Fe- or Mn-superoxide dismutases from aerobic organisms.

In vivo incorporation of cobalt into Propionibacterium shermanii superoxide dismutase

FEBS Letters ◽  
1994 ◽  
Vol 348 (3) ◽  
pp. 283-286 ◽  
Author(s):  
Beate Meier ◽  
Anja P. Sehn ◽  
Marco Sette ◽  
Maurizio Paci ◽  
Alessandro Desideri ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Propionibacterium Shermanii

scholarly journals pH-dependent inhibition by azide and fluoride of the iron superoxide dismutase from Propionibacterium shermanii

1998 ◽  
Vol 331 (2) ◽  
pp. 403-407 ◽  
Author(s):  
Beate MEIER ◽  
Christoph SCHERK ◽  
Marius SCHMIDT ◽  
Fritz PARAK
Keyword(s):  
Superoxide Dismutase ◽  
Active Site ◽  
Low Ph ◽  
Superoxide Dismutases ◽  
Iron Superoxide Dismutase ◽  
Propionibacterium Shermanii ◽  
Hydroxyl Anion ◽  
Dependent Inhibition ◽  
Ph Dependent ◽  
A Minor

The iron-containing superoxide dismutase from Propionibacterium shermanii shows, in contrast with other iron superoxide dismutases, only a minor inhibition by azide or fluoride (10–100 mM) of up to 23% at pH 7.8. The activity of the protein with Mn bound to the active site was not diminished under the same conditions. The binding constant between azide and the Fe3+ ion was determined as approx. 2 mM and for fluoride approx. 2.3 mM; they are so far comparable to those known for other iron superoxide dismutases. This seems to be a discrepancy because all other iron superoxide dismutases so far known are described as being inhibited by 50–70% by 10 mM azide. However, towards lower pH there was a drastically increased inhibition by both anions. At pH 6.8 about 80% inhibition was exhibited by azide or fluoride at a concentration of 10 mM or higher. In contrast, on increasing the pH, azide or fluoride still bound to the Fe3+ at the active site but their inhibition capacity decreased. This observation implies that both anions bind to the metal at a position that is empty at low pH, whereas at higher pH water or a negatively charged hydroxyl anion is bound. It is likely that the superoxide anion binds to the same position and has to replace the sixth ligand, leading to a diminished catalytic activity of the superoxide dismutase owing to steric and/or electrostatic inhibition of the ligand.

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